Method of making an electrical rapper



Nov. 11, 1969 I v WEARCHER M 3,477,124

METHOD OF MAKING AN ELECTRICAL RAPPER 7 Filed 001;. 7, 1965 I v v E v I 2 Sheefi-Sheec 1 22 v I J I -25 Z INVENTOR WILLIAM E. ARCHER LEO O. REED ATTORNEY EVERETT L. COE JR. I

, Nov. 11,1969 W ARCHER ETAL 3,477,124

METHOD OF MAKING AN ELECTRICAL RAPPER Filed Oct. '7, 1965 2 Sheets-Sheet 2 I mmvroxs' v WILLIAM E. ARCHER I EVERETT L. coE JR .1 v I I LEO o. REED v & I f yg A: fizz a ATTORNEY United States Patent METHOD OF MAKING AN ELECTRICAL RAPPER William E. Archer, Portuguese Bend, Everett L. Coe, Jr.,

Downey, and Leo 0. Reed, Covina, Califi, assignors to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 7, 1965, Ser. No. 493,689

Int. Cl. H0 1f 7/06; H02k 15/00 US. Cl. 29 592 9 Claims ABSTRACT T HE DISCLOSURE A method of making a magnetic assembly by forming a subassenibly which is potted in an outer surrounding structure.

become apparent upon consideration of the following de" y scription and drawings in which:

FIG. 1 is a cross-sectional view of a magnetic circuit assembly as used in an electrical rapper constructed in accordance with the principles of this invention.

FIG. 2 is a cross-sectional view of an inverted and partially encased magnetic circuit assembly as shown in FIG. 1;

FIG. 3 is a partial side elevationaland partial crosssectional view of a fully encased magnetic circuit assembly as shown in FIG. 1 and including "an'electrical terminal. i

FIG. 4 is a top plan view of a structure shown in FIG. 3;

FIG. 5 is a cross-sectional view of an electrical rapper constructed in accordance with the principles of this invention with portions thereof being shown in elevation.

FIG. 6 is a front elevational view ofa hammer hearing as used in the structure of FIG. 3;

FIG. 7 is a side elevational view of the structure shown in FIG. 6;

FIG. 8 is a side elevational view of the lower portion of the structure shown in FIG. 5;

Referring to FIG. 1, it will be noted that a magnetic circuit assembly constructed in accordance with the principles of this invention comprises a tubular solenoid coil 2 which is closely wound, either wet or dry, around atubul ar coil spool 4 with the ends of the spool 4extending axially beyond the ends of the coil 2. Coil 2 and spool 4 are formed from suitable material in any suitable manner as is well known. As shown, the coil 2 and spool 4 are received in a housing comprising a tubular side sealant becomes cured.

3,477,124 Patented Nov. 11, 1969 ice any suitable form and has a downwardly extending tubular portion 16 having an upwardly extending coaxial recess 18 therein. The outer periphery of the plate 8 is also provided with a circular notch 20 in the downwardly facing portion thereof with the sides thereof being perpendicular to each other.

In assemblying the above described magnetic circuit assembly peripheral beads of a suitable sealant, such as a silicone rubber sealant sold by the Dow Corning Corporation as Silastic RTV732, are placed at the juncture of the sides of notches Hand 20, at the juncture of the portion 16 with the upper portion of the plate 8 around tube 4 at a point where plate 10will cover it when tube 4 is subsequently inserted into opening 12 to smear the sealant between spool 4 and plate 10. Thereafter, side 6 is inserted over the coil 2 and the upper plate 8 placed on the top of side 6 with the projection.16 being closely received within the spool 4. When so assembled coil 2 is located intermediate plates 8 and 10 inwardly "of side 6. Suitable openings 22 which communicate with the chamber 24 between the coil 2 and side 6 are provided in plate 8.

The assembly is next clamped in any suitable manner so that side 6 is squeezed between plates 8 and 10 and spool 4 is forced against the sides of opening 12, and into engagement with plate 8. The internal diameter of side 6 is slightly larger than the diameter of the upwardly extending side of notch 14 so that such squeezing causes the sealant to flow out from under the ends of side 6 and metal to metal contact is obtained between the ends of side 6 and plates 8 and 10. Such squeezing also causes the sealant to flow between the upper end of the spool 4 and underside of plate 8: The assembly with the squeezing force constantly being applied is held until the and Manufacturing Company patented under US. Patent 3,052,650, Bulletin 08-074 of February-1964 of Dow Corning describes the aforementioned Silastic 732 RTV Silicone Rubber. Such epoxy ispoured into one of the openings 22 until the cavity 24 is filled from the upper surface of plate 10 to at least above the upper end of coil 2. The entire cavity 24 is preferably filled and desirably openings 22 are also filled. In filling, proper care is taken to insure that no air entrainment occurs in the epoxy and thereafter the entire clamped and filled assembly is heated to curethe epoxy as is well known. Upon curing of the epoxy the epoxy permanently mechanically bonds the coil 2, spool 4, plates 8 and 10, and side 6 into a single unitary. structure. With the epoxy indicated an assembly is produced which is isolated from ambient moisture conditions, mechanically stable,"rnag- 3 netically solid, and has the desired heat conductivity to the side 6 and plates 8 and 10.

The plates 8 and 10 are of any desirable form to be assembled as heretofore described; however, for the purpose of this description the lower plate 10 is of a circular cross-section and the upper plate 8 (see FIG. 4) has the greater part of its outer periphery directly overlying the outer periphery of plate 10. Plate 8 is also provided with circumferentially spaced portions spaced inwardly of the outer periphery of plate 10 for a purpose as hereafter described.

In order to encase the magnetic assembly, a tubular casing 26 (see FIG. 2) is provided having a circular outwardly extending periphery flange 28 at each end thereof. Casing 26 has an internal diameter slightly larger than the diameter of the plate 10 so as to freely receive the magnetic assembly therein. As shown in FIG. 2, the magnetic assembly is inverted and supported within the inverted casing 26 by a suitable spacer block 30 with the coil 2 leads extending downwardly. Thereafter a bead 32 of sealant such as the aforementioned Silastic RTV 732 is peripherally applied at the juncture of the plate 10 and the casing 26. After the bead 32 is applied the assembly remains for a suflicient period of time to permit I curing of the-Silastic RTV732 to provide a mechanical bond and seal between the plate 10 and the casing 26. After curing of the head 32 the casing 26 is turned upright (see FIG. 3) and a suitable terminal block 56 is located on top of plate 8 with the base of block 56 being located upwardly of the upper surface of plate 8, block 56 supports terminals 57 of any suitable structure having conductor portions (not shown) located in the space between the undersurface of block 56 and the plate 8 to which the electrical conductors from coil 2 are suitably electrically and mechanically secured. Casting resin epoxy such as the aforementioned Scotchcast number 281, is poured between the magnetic assembly and the casing 26. The portions of plate 8 spaced inwardly of the periphery of plate 10 provide openings 33 (see FIG. 4) between the plate 10 and casing 26. The liquid casting resin is poured through one of the openings 33 with the air being permitted to escape through the other of such openings 33. The epoxy is prevented from flowing past the magnetic assembly by the bead 32. Liquid casting resin epoxy is poured until the entire cavity 90 between the magnetic assembly and the casing 26 is filled. An upper cap portion 34 of epoxy I is also poured above the plate 8 and if an opening or openings 22 have not been previously filled they are filled at this pouring of epoxy. Cap portion 34 encapsulatesthe conductors from the coil 2, the lower portion of terminals 57 and rigidly secures the block 56 to the magnetic assembly. The epoxy is oven cured after pouring as is well known.

After securing the magnetic assembly to the casing 26 l a hammer 36 having a spring 46 therein is inserted into the lower portion of the casing 26 (see FIG. 5). Hammer 36 is of known construction comprising a lower cylindrical body portions 38 of a diameter to be closely received with the casing 26. An intermediate reduced diameter portion 40 of hammer 36 extends coaxially upwardly from the body portion 38 and provides an annular shoulder 42 therebetween. An upper reduced diameter portion 44 extends coaxially upwardly from portion 40 and has an annular shoulder 45 intermediate its length. Upper portion 44 has its upper end formed to be closely received within the recess 18 and when coil 2 is deenergized the upper end of portion 44 is biased away from the recess 18 by means of the coil spring 46 surrounding the lower portion of portion 44 and the portion 40 plus the action of gravity. The ends of spring 46 engage the shoulder 42 and the lower surface of the plate 10 respectively. A suitable resilient bumper 49 is provided to prevent tapered end of hammer from impacting in tapered section 18. The bumper 49 is secured to shoulder 44 and I --4 iextends upwardly therefrom and circumferentially therearound to engage the lower surface of plate 10 inwardly of the coils of spring 46 upon energization of the coil 2. The heretofore described structure of hammer 36 is well known as the operation thereof.

Upon energization and deenergization of the coil 2, hammer 36 moves upwardly and downwardly, respectively, in casing 26 and in keeping with the invention a novel bearing 48 is provided between the body portion 38 and the inner surface of casing 26. As also shown in FIGS. 6 and 7, bearing 48 comprises a strap of narrow width compared to the length thereof with one side being smooth and the other side being provided with a tooth formation 50. Bearing'48 is of any suitable material such as nylon to slide freely within the casing 26. The body portion 38 is provided with a peripheral groove 52 of a width to closely receive the bearing 48 therein with the outer ends of the tooth formation extending outwardly of the outer periphery of the body portion 38. The groove 52 and bearing 48 are of a depth and size so that the outer ends of the tooth formation 50 slideably engage the inner surface of the casing 26. With such structure as the hammer 36 moves in opposite axial direction within casing 26 no air is trapped between the magnetic assembly and the hammer 36 due to the passageways between the adjacent teeth of the tooth formation 50. Since the tooth formation 50 provides' air vent'passageways, centrally positions and guides the hammer 36 in casing 26 the teeth of the tooth formation 50 are of any suitable form for such purpose such as the buttress or sawtooth form shown.

n The upper end of casing 26 is provided with an openmg in which a suitable wiring gland 54 is located and through which the electrical supply lines extend to and are suitably secured to the exposed terminals 57 on the block 56 to insure proper electrical operation of the coil 2.

A removable cap 60 is provided to close the upper end of the casing 26. Cap 60 comprises a shallow dished clrcular member having an outwardly extending peripheral flange -62 which is the same or substantially the same circumference and radial extent as flange 28 to receive a suitable annular resilient gasket 64 therebetween. Cap 60 is secured to casing 26 by means of a split ring clamp 66 having a generally U-shaped cross-section which is inwardly open and surrounds the flanges 62 and 28. The sides of clamp 66 slope away from each other and the ends Ofthe clamp sides are provided with an outwardly extending flange portion 68. Clamp 66 is also provided with two outwardly extending flanges 70 at the free ends of the clamp and which flanges 70 are drawn together into substantially abutting relationship in any suitable manner such as by a bolt and nut assembly72. With such structure the clamp 66 encircles the flanges 62, and 28 with gasket 64 therebetween and is drawn together by assembly 72 so that the sides of the clamp engage the outer edges of flanges 62 and 28 to force the flanges 62 and 28 towards each other and thereby compress the gasket 64 therebetween. When so clamped flanges 68 prevent dirt and water from entering the. casing 26.

A shaft mount assembly. (see FIG. 8) is secured to the lower end of casing 26. As shown, the shaft mount assembly comprises a hollow tubular housing 74 having an outwardly extending peripheral flange 76 of the same size as the lower flange 28 and has a gasket portion formed on the upper surface thereof. A ring 66 is employed to secure the shaft mount assembly tothe casing 26 in the same. manner as cap 60 is secured to the casing 26.

The shaft mount assembly is also provided with a tubular shaft guide 78 coaxially with and spaced radially inwardly of the housing 74. Guide 78 extends downwardly from the lower end of housing 74 and has transversely aligned openings therein to receive a pin 80 for locking an anvil. shaft 81 (shown in phantom) with respect to the entire rapper assembly. The guide 78 ,is secured to the housing 74 by means of a mass 82 of rubber which is annular in cross-section and bonded to the guide 78 and housing 74 as shown in any suitable manner such as being vulcanized thereto. The mass 82 is described as rubber; however, any suitable material such as neoprene having the resiliency, and moldability of rubber is satisfactory. The mass 82 is also provided with an outwardly extending peripheral gasket portion 84 at its upper end to provide a gasket between the flanges 28 and 76, and an inwardly extending peripheral flange portion 84 to provide a resilient O-ring seal around the anvil 81.

Thus, it will be seen that this invention provides an inexpensive rapper housing which can readily be field assembled and disassembled; a shaft mount assembly which provides an anvil seal, an integral gasket, a shock absorber between the housing and the anvil, and permits the use of a single transverse pin to secure the anvil thereto; an inexpensive guide bearing for the hammer; and an extremely stable operating coil under all adverse environments in which a rapper is used.

Having described a preferred embodiment of this invention, it is to be realized that modifications thereof may be made without departing from the broad spirit and scope of the invention. Accordingly, it is respectfully requested that the claims appended hereto be interpreted as broadly as possible and be limited only by the prior art.

What we claim is:

1. A method of assembling a magnetic structure including, a tubular metal spool member having an externally encompassing magnet coil intermediate the axial ends thereof, a tubular metal side member surrounding and spaced outward from said coil, and first and second metal end plates located at opposite end portions of said member and forming a space encompassing said coil in conjunction with said members, comprising the steps of: emplacing peripheral beads of hardenable sealant at the juncture areas of the end portions of said spool member and said side member with said end plates; forming continuous seals between said end plates and said end portions by placing said end plates into contact with said end portions of said spool member and said side member and smearing said beads of sealant; clamping said end plates with said side member therebetween to establish metal to metal contact between said end plates and said member; curing said sealant to form a liquid tight seal between said end plates and said members; filling the said space with an epoxy casting resin in liquid form; and unclamping said end plates when said casting resin has solidified, to form a unitary magnetic structure.

2. A method of assembling a magnetic structure as specified in claim 1 wherein at least one of said end plates have portions adjacent the outer periphery thereof to locate said side member with respect to said coil.

3. A method of assembling a magnetic structure comprising the steps of: emplacing a first peripheral head of hardenable sealant about one end portion of a tubular central metal spool member having a cylindrical magnet coil intermediate the axial ends thereof; inserting said end portion into a central opening of a first metal end plate to smear said bead into a continuous seal between said end plate and said end portion; emplacing a second peripheral bead of such sealant on said end plate intermediate said central opening and the outer periphery thereof; placing an end of a metal tubular side member surrounding and spaced outwardly from said coil against said end plate to smear said second bead into a continuous seal between said side member end and said first end plate; emplacing third and fourth peripheral beads of sealant on a second end plate; placing said second end plate closely adjacent the other ends of said spool member and said side member to smear said third and fourth beads, respectively, into continuous seals between said second end plate and said spool member end and said second end plate and said side member end; clamping said end plates with said side member therebetween to establish metal to metal contact between said end plates and said side plate; curing said sealant; filling the space between said spool member and said side member with an epoxy casting resin in liquid form; and unclamping said end plates when said casting resin has solidified, to form a unitary magnetic structure.

4. A method of assembling a magnetic structure as specified in claim 3 wherein at least one of said end plates have portions adjacent the outer periphery thereof to locate said side member with respect to said coil.

5. A method of assembling an electrical rapper comprising the steps of: inserting an elongated magnetic subassembly having an outwardly extending portion at one end thereof, into an elongated tubular housing extending axially beyond said one end and other end of said subassembly and defining a space between said housing and the external periphery of said magnetic subassembly; supporting said magnetic assembly in the desired position within said housing; emplacing a continuous peripheral bead of sealant at the upper end of said space between the outer periphery of said outwardly extending portion and the inner periphery of said housing; curing said peripheral bead; filling said space with liquified resin; allowing said resin to overflow and cover said other end; and solidifying said casting resin.

6. A method of assembling an electrical rapper as specified in claim 5 wherein said magnetic subassembly further includes a tubular metal spool member having an externally encompassing magnet coil intermediate the axial ends thereof, a tubular metal side member surrounding and spaced outward from said coil, and first and second metal end plates located at opposite end portions of said members and forming a space encompassing said coil in conjunction with said members, and is made by: emplacing peripheral beads of hardenable sealant at the juncture areas of the end portions of said spool member and said side member with said end plates; forming continuous seals between said end plates and said end portions by placing said end plates into contact with said end portions of said spool member and said side member and smearing said beads of sealant; clamping said end plates with said side member therebetween to establish metal to metal contact between said end plates and said side member; curing said sealant to form a liquid tight seal between said end plates and said members; filling the said encompassed space with an epoxy casting resin in liquid form; and unclamping said end plates when said casting resin has solidified to form a unitary magnetic subassembly.

7. The method of making an electrical rapper as set forth in claim 5 wherein electrical conductors, communicating with said subassembly, extend between said subassembly and a terminal block mounted on said other end and said resin overflow covers said conductors and the connection between said conductors and said terminal block but leaves the terminals of said terminal block exposed above the surface of said resin overflow.

8. The method of making an electrical rapper as set forth in claim 7 wherein said housing has a radially outwardly extending flange on a first end thereof outwardly adjacent said one end of said magnetic subassembly and including the additional steps of: emplacing a cap member having a similar flange on one end; inserting a gasket between said flanges; and clamping said flanges with a ring type clamp having inner surface engaging said flanges and basing said flanges into engagement with opposite sides of said gasket.

9. The method of making an electrical rapper as set forth in claim 8 wherein said housing has a radially outwardly extending flange on the second end thereof and including the additional steps of inserting an elongated stepped cylindrical hammer into said second end of said housing and partially into said magnetic assembly; emplacing a shaft mount assembly having a similar flange on one end thereof against said second end flange; and

clamping said second end flange to said one end flange with a ring clamp as described in claim 8. I

References Cited UNITED STATES PATENTS Immel 335-260 Drenning 55-112 Tierney 29-605 X Procopio 29-605 X Sutton 336-92 Baier et a1. 335-260 Erickson 335-260 Davis 336-96 8 Erickson et a1. 335-260 Waldschmidt. Bettridge 264-272 X Glickman 264-272 X Larsen et a1 264-272 X Jo'HN'F. CANPBELL, Priniary Examiner D. C. REILEY, Assistant Examiner US. Cl. X.R. 

